Well , mistery SOLVED.
After upgrading to 81.10 , the respective gateway was automatically REMOVED from my IPS / Threat prevention policy ????
I just upgraded another one and I noticed that the gateway was removed from the IPS policy after upgrade ?
Pushed policy ... fail.
Checked the IPS / Threat prevention policies and the gateway was NOT on any policy.
Added the gateway to the policy again , pushed policy and all went fine.
I have a policy for the small appliances and the next upgraded gateway vanished from the targets for that policy ... so no wonder the management server came and told me "No profile defined on GW" .. as there was no policy defined for that gateway so there was nothing to push..
I guess this can be defined as a Bug ? Why should a gateway remove itself from the policy after upgrade without any warnings ?